1. Field of the Invention
This invention concerns an industrial robot and, particularly, it relates to a so-called teaching-playback type industrial robot.
2. Description of the Prior Art
A linear interpolation type teaching-playback type industrial robot is known. In the case of conducting, for example, a coating operation by the industrial robot of this type, the top end of an industrial robot main body having an injection nozzle is first moved over the entire surface to be worked by an operator so as to simulate a coating operation for an object to be coated and, at the same time, the contents of the simulated operation, which are issued at a predetermined interval in distance, are stored into a memory device (generally referred to as point-to-point (PTP) teaching operation). Then, after all of the operation contents have been stored, the coating operation is repeated automatically again by reading out the stored data for the operation contents in two positions spaced by the predetermined distance and additionally preparing position data by dividing the interval between the two position data linearly into a predetermined number with the thus read out two position data, that is, the coating operation is carried out accompanying the linear interpolation operation (generally referred to as playback operation).
U.S. Pat. Nos. 4,385,358 and 4,420,812 are referred to, for example, as publications showing such technics in the prior art.
If the contents of the workings in the predetermined working positions on the worked surface are sequentially stored in the memory device upon a teaching operation in the industrial robot, the teaching operation is required to be executed in order to cover the surface to be worked while repeating the linear reciprocal movement over the entire surface to be worked, which results in the increase in the amount of time required to perform the teaching operation and, in addition, increases the physical burden of the operator. Further, the correction for a portion of the contents of the working taught to the robot is carried out by conducting the similar teaching operation again and storing all of the contents of the working including the partial correction again to the memory device. Accordingly, the teaching-playback type industrial robot of a linear interpolation type in the prior art is not always efficient in its operation.
Furthermore, in the coating or like other working, it is, for instance, necessary linear loci be drawn in the longitudinal and lateral directions during the teaching operation so as to eliminate uneven coating on an identical surface to be worked thereby requiring a greater amount of working time and thus increasing the operator's burden.